Medusa Nozzles

[Bruce]

What are the advantages of the multi throat Medusa nozzles for rocket motors?

On the surface, it would seem like more throats would complicate the nozzle design and make it weaker / heavier.

I saw that the old "Tiny Tim" motors used a medusa nozzle. Here's a picture from:

https://wiki.warthunder.com/Tiny_Tim

 

[Antares JS]

My understanding is that it's a manufacturing thing - it reduces the number of nozzle molds needed. Just produce a bunch of Medusa nozzles and drill as many throats as you need to get the throat area needed by the motor instead of manufacturing a bunch of different nozzles.

 

[dhbarr]

They're short.

 

[Antares JS]

They're short.

That too.

 

[Bruce]

Do they produce a broader flame pattern?

 

[Antares JS]

Do they produce a broader flame pattern?

Than a single throat? I doubt it, but I don't know for sure.

 

[dhbarr]

Do they produce a broader flame pattern?

The base of the flame is certainly broader
https://static.fw1.biz/templates//170652/myimages/rcs_01700_nozzle_dwg.pdf

 

[Antares JS]

The base of the flame is certainly broader
https://static.fw1.biz/templates//170652/myimages/rcs_01700_nozzle_dwg.pdf

Are you talking about right at the exit plane of the nozzle? Again, I doubt it because the exit area of a single-throat nozzle is going to be just about as wide as the medusa nozzle. Depending on the specific geometry of the nozzle the medusa might be a little bigger, but I doubt it would really be noticeable.

 

[dhbarr]

Are you talking about right at the exit plane of the nozzle? Again, I doubt it because the exit area of a single-throat nozzle is going to be just about as wide as the medusa nozzle. Depending on the specific geometry of the nozzle the medusa might be a little bigger, but I doubt it would really be noticeable.

The area is the same, I'm just talking about the spacing between the throats.

 

[Antares JS]

The area is the same, I'm just talking about the spacing between the throats.

To produce a broader plume though, the width of the exit area would need to be wider vs. a single throat nozzle. This is not the case.

 

[dhbarr]

To produce a broader plume though, the width of the exit area would need to be wider vs. a single throat nozzle. This is not the case.

Even if you open up all the throats there's still nonzero web thickness at the exit, right?

 

[3stoogesrocketry]

What are the advantages of the multi throat Medusa nozzles for rocket motors?

On the surface, it would seem like more throats would complicate the nozzle design and make it weaker / heavier.

I saw that the old "Tiny Tim" motors used a medusa nozzle. Here's a picture from:

https://wiki.warthunder.com/Tiny_Tim

View attachment 452297

The tiny tim was a all surface burn motor if I recall . All but the center hole was open . The center was a burst disk in case of over pressurization . It was the booster stage of the Wac Corporal , and burnt out before it left the 100 foot tower.

 

[Steve Shannon]

They're short.

I think that’s it in a nutshell. A single nozzle of equivalent area would be much longer.

 

[Rocketjunkie]

Medusa nozzles were shorter than the single throat nozzle for motors 54 mm and up.
For Rx motors, I like Medusa nozzles. For 54 mm:
Determine Kn you want to operate the motor at. Calculate single throat nozzle size.
If under around 3/8",use small hole closure and 29 mm nozzle. (Not an option for 75 and 98 mm motors)
If under about 9/16" use 1/2 the area in the center and the rest spread among 3 outer throats.
Otherwise, use 1/3 the area in the center and the rest spread among the other 6 throats.
I haven't experimented with 2 or 4 outer throats or just outer throats with center throat holding the rod in a rod and core burner.

 

[AeroTech]

It was originally a way to make a wide variety of nozzles using only a single nozzle mold as Antares said.